My favorite thing about The Big Bang Theory Season 8 Episode 17 is the time spent on Penny and Leonard's relationship. Especially since it involves sexy body painting.
Sometimes it's easy to forget why Penny and Leonard actually make a fantastic couple.
A lot of the humor in the show deals with their differences. which makes sense since that's the foundation of the series. But in "The Colonization Application" we see them function as a regular couple who has grown together in a perfect way.